In the past 15 years, ruthenium olefin metathesis catalysts have firmly established olefin metathesis as a versatile and reliable synthetic technique for organic syntheses. The exceptionally wide scope of substrates and functional group tolerance makes olefin metathesis a valuable technique. In this application, the use of olefin cross metathesis to produce alpha-olefins is another example of the usefulness and the robustness of olefin metathesis technology. Compared to traditional synthetic organic techniques, olefin metathesis efficiently produces compounds that are otherwise hard to synthesize. Numerous man hours of research have resulted in the elucidation of many olefin metathesis reactions catalyzed by various transition metal complexes. In particular, certain ruthenium and osmium carbene compounds, known as “Grubbs' catalysts,” have been identified as effective catalysts for olefin metathesis reactions such as, for example, cross-metathesis (CM), ring-closing metathesis (RCM), ring-opening metathesis (ROM), ring opening cross metathesis (ROCM), ring-opening metathesis polymerization (ROMP) or acyclic diene metathesis (ADMET) polymerization.
ROCM is a version of cross metathesis and historically has been underutilized mainly due the difficulty of controlling selectively. ROCM is an intermolecular exchange of a cyclic olefin and an acyclic olefin. In these instances, release of ring strain is the driving force for the reaction to proceed. A review of ROCM is provided by Schrader and Snapper in Handbook of Metathesis, Volume 2: Applications in Organic Synthesis (R. H. Grubbs Ed.), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2003, pp 205-237.
Early ROCM examples were low yielding reactions with poor selectivities. Even with these shortcomings, ROCM has become an important fixture in metathesis history because ROCM was the key reaction used by Yves Chauvin to propose the currently accepted metathesis mechanism that bears his name, i.e. the Chauvin mechanism. Chauvin proposed the interchange of metal carbenes via a metallocyclobutane ring as an alternative mechanism to the then-accepted pair-wise mechanism for olefin cross metathesis. The metallocyclobutane mechanism was proposed based on the ROCM of cyclopentene with 2-pentene, shown in Scheme 1, which resulted in a statistical product distribution (1:2:1 of compounds 1, 2, and 3 respectively). In the pair-wise mechanism only compound 2 would be expected to form, at low conversions. Chauvin was rewarded for his insight and contributions to metathesis by sharing the 2005 Nobel Prize in Chemistry with Dr. Robert Grubbs and Dr. Richard Schrock.

ROCM reactions using cyclododecene and methyl oleate or oleyl acetate have been reported. The reactions employed an ill-defined tungsten catalyst system to produce the ring inserted product, as shown in Scheme 2.

There is an ongoing need in the art for methods and systems that would allow ring insertion cross metathesis of cyclic olefins into internal olefins, e.g., seed oils and the like. This type of reaction would be useful in the preparation of various useful products, including, by way of example, chain-extended trialkylglycerides (TAGs) and chain-extended fatty acid methyl esters (FAMEs). An ideal such reaction could be implemented in the preparation of metathesis products useful as binders in urethane foams, latex pains, printing inks, and high melting point waxes.